In curiosity. 4 just doesn't fit with the context? Or grammatically wrong?
I suppose it's former. This "until" suggests there would be a change thereafter, and in this sentence it means he/she quitted his/her learning despite from the situation that he/she likely to need english. So this sentence sounds odd. In other words, the sentence could be valid if there is a hint of why he/she quitted it. Am I right?
"Until I came to the USA, I had learnt some English. However I soon found that my native tongue is being accepted widely there and the fact I wouldn't have much troubles in daily life even without english." or something.
1-when... means ( first i went to USA, and then, I learned English.)
2-by the time... means (I started learning English before going to USA, and when i arrived there, I was able to speak English.)
3-Before... means(when i started learning English, I didn't have any plan to go to USA, And when i arrived there, I was able to do whatever I want with my English.)
4- sorry, i have nothing to say. I'm not even sure if it is correct or not.
Well, I understand this example sounds more natural.
I just a bit worried. Because this sentence didn't look a definite mistake to me, probably following sentence would be different though, I wondered if there was any grammatical mistake that I didn't notice.
Anyway, thank you tdol, for sparing your time. (Not only this topic)